Finally, our finding that YAP1 expression is downstream of RB1 signaling may provide a missing mechanistic link in generating the ‘classic’ SCLC phenotype as RB1 expression is lost in the majority of SCLC and also during acquired resistance to erlotinib in NSCLC to SCLC transformation [30]. This evidence concerns the gene RB1 and non-small cell lung carcinoma.